docs: on-impact particles + On Impact node + throwing (PFX-C)

Author: AlexZ005

docs/nodes/onimpact.md

@@ -0,0 +1,30 @@
+# On Impact
+
+Fires a pulse when a [physics simulation](../physics.md) lands the connected object on the ground or another object.
+
+**Output:** event (wire into a [Particles](particle.md) trigger, a [Counter](counter.md), or an [Object Selector](objectselector.md))
+
+## How it works
+
+While a simulation runs, the peer stepping the physics detects each real contact — a falling crate hitting the floor, a thrown ball hitting a wall — and pulses this node for **everyone** (the trigger rides the same replicated stamp as [On Click](onclick.md)). Gentle settling and rolling are filtered out: the object must actually be falling, and each object has a short cooldown so bounces don't spam.
+
+## Parameters
+
+| Parameter | Default | Meaning |
+|---|---|---|
+| minStrength | 1 | minimum impact speed (m/s, downward at contact) — raise it so only hard landings count |
+
+## Targeting
+
+Like On Click, the node fires for the object it *reaches* in the graph: wire it into an [Object Selector](objectselector.md) (directly or through other nodes), or drop it unwired inside an object's own flow to target that object.
+
+## Practical example
+
+Sparks + a thud when a crate lands:
+
+1. Give the crate a **Dynamic** body (Inspector ▸ Physics).
+2. In its flow: **On Impact → Particles** (`trigger` input, emission *burst*, preset *Sparks*), and **On Impact → Counter** if you want to count landings.
+3. Press <kbd>P</kbd>, lift the crate with the gizmo, drop it. Sparks on landing, for every peer.
+
+!!! note
+    Simplest version, no flow editor at all: set a particle emitter's **Emission** to *On impact* in the Inspector — see [Particle Effects](../particles.md).

docs/particles.md

@@ -36,10 +36,14 @@ Right-click empty space ▸ **Add ▸ Effects ▸** places a small marker object
 
 A preset is just a starting point — every value below is editable afterwards.
 
-## Continuous vs burst
+## Continuous, burst, and on-impact
 
 - **Continuous** emitters (Sparkles, Fire, Smoke) emit forever.
-- **Burst** emitters (Dust puff, Confetti, Sparks) fire all their particles at once, then wait for the next trigger. They auto-fire once when you attach them so you get instant feedback; after that, replay them with **💥 Burst now**, wire an event into the [Particles node](nodes/particle.md), or — coming soon — let them fire automatically when an object hits the ground.
+- **Burst** emitters (Dust puff, Confetti, Sparks) fire all their particles at once, then wait for the next trigger. They auto-fire once when you attach them so you get instant feedback; after that, replay them with **💥 Burst now** or wire an event into the [Particles node](nodes/particle.md).
+- **On impact (physics)** emitters fire automatically when a [physics simulation](physics.md) lands the object on the ground or another object — a dust puff exactly when the crate hits the floor. Set the object's body to **Dynamic**, set the emitter's **Emission** to *On impact*, and press <kbd>P</kbd>. Every peer sees the same burst. Small settling bounces are filtered out (the object has to be actually falling), and a rolling object won't machine-gun bursts.
+
+!!! tip "Throwing things"
+    While a simulation runs you can **grab and throw** any dynamic object — drag it with the gizmo on desktop, or grip-grab it in VR — and it flies off with the velocity of your hand when you let go. Heavier objects (higher **Mass**) hit harder. Combine with an on-impact emitter for very satisfying crashes.
 
 ## Properties
 

mkdocs.yml

@@ -44,6 +44,7 @@ nav:
       - Visibility: nodes/visibility.md
       - On Click: nodes/onclick.md
       - Key Press: nodes/keypress.md
+      - On Impact: nodes/onimpact.md
       - Counter: nodes/counter.md
       - Shake: nodes/shake.md
       - Spin: nodes/spin.md